The Nathan/William thing. A few reasons. 1.) I rather liked Eureka and Colin Ferguson, so there's the aesthetic thing going on there, especially with the kind of similar look that the two guys have, both got that rangy cowboy thing going on and the blue eyes? 2.) Occasionally I just dig the villain 'ships generally, especially when the characters have some sort of past connection or crucial interest in common that makes them reflections of each other (or of the other's romantic obsession). Reed Richards/Doom, Crichton/Scorpius, Luffy/Crocodile, Fred/Lilah... 3.) On from that they do have that connection, over Audrey|Mara, and so the presence of William offers a male character and opportunity for slash that Nathan can feel, who can mess him up just as much as Audrey|Mara(|Sarah) can.
4.) It's kind of fun? William's a cheerful, villainous nutter of few morals and Nathan is... well, it's not that he doesn't have a sense of humour, but it's rather dry and in certain situations you'd have to look hard to find it, but he's definitely the serious straight man, so the idea of saddling him with this zany, cheerful character is pretty neat.
I tend to see this 'ship as dub/non consent more than anything else, so it was a challenge to write it when I knew the requester didn't want that, and find a way to make it work for me with that element removed (mostly. I guess there'll always be shadows of that in the identity issues thing). I have to admit that the concept of Aaron Pallister makes me grin like an idiot and, okay, maybe it skews the gender issues in the show horribly to take out Audrey and leave Mara the villain, but it's a thought experiment. We are allowed those from time to time. I think I've written enough things that Audrey was central to, to get away with this one.
I'm not sure why this one's been struggling so much, because as I say, I like it a lot. Maybe it's the gender issues, maybe it's the tense change and switch to flashback two paragraphs in (I needed the background to sell the aftermath... I had something like 3 days to write the fic by the time House Divided and Troubled Tales were finished and I'd worked past the dead-slump that followed...eep!... so I didn't have time to play around with different ways of doing that).
I thought about tagging it 'curtain fic' in a totally ironic way. It ended up more domestic in focus than I'd expected. But in the end it wasn't about a dramatic fists-and-Troubles-and-superpowers fight for "Aaron's" identity, but a guy trying to figure out who he was and what environment he belonged in and who with. Which I think is more interesting than I could've made all the melodrama and Nathan shouting "Aaron, come back to me!" a lot.
I guess it begs the question of why I've never done this approach with Audrey|Mara/Nathan. And I think that's got to be the gender issues. Put a woman in that situation, with the mind-wipe, and fling her body to someone else's control like that, and it feels a lot more rapey, it feels like Mara's anger is right. Maybe that's a position/attitude worth examining? I'm usually more equal in my treatment of the sexes than that. But there's just as much an argument that Mara WAS those personalities and that under the circumstances those were her choices (with misinformation, but still her choices). IDK. It's an odd one. Would people be squicked if I'd written this sort of situation with Mara just falling for Nathan post-personality-wipe? At least one story out there already that seems to be popular enough to indicate not. But Mara falling for Nathan feels so much more tricky and landmine peppered in all the issues it raises. (Which is why Eurydice|House exists...) For me that needs to be more than the question of "love" saving/redeeming Mara... particularly of Nathan's love, which was never consensual from Mara's perspecfive to begin with.
Which is obviously inherently different from William deciding "Hm, I've got a good thing going here, I'm comfortable, this identity has been good for me, maybe I'll leave the evilin' days behind and try this on..."
(It's probably a question of gravitas as well. Mara intrinsically has more drama in her evil, twisted soul, while William's presence is lighter and more easy-going.)
Sometimes things get way more complicated than they seem.